import { useCallback, useEffect, useMemo, useRef } from 'react';
import { useEditor } from '@craftjs/core';
import type { DeviceMode } from '../types';
import { useDevice } from '../state/DeviceContext';
import { usePages } from '../state/PageContext';
import { useSitesmithModal } from '../state/SitesmithContext';
import { useNotices } from '../state/NoticeContext';
import { useMobileChrome } from '../state/MobileChromeContext';
import { isTypingTarget, matchShortcut } from '../utils/shortcuts';

/**
 * Command registry: one place where features register what they can do, shared
 * by the keyboard layer, the Cmd+K palette, the top-bar "More" menu and the
 * breadcrumb. Module-level (like hooks/clipboard.ts); features register from an
 * effect via `useRegisterCommands` and never edit TopBar / useKeyboardShortcuts.
 */
export type CommandGroup = 'edit' | 'select' | 'view' | 'insert' | 'page' | 'site' | 'help';

export interface CommandContext {
  query: any;
  actions: any;
  selectedIds: string[];
  device: DeviceMode;
  setDevice(d: DeviceMode): void;
  pages: ReturnType<typeof usePages>;
  notify: ReturnType<typeof useNotices>['notify'];
  openSitesmith(target?: any): void;
  openTemplates(): void;
  openHeadCode(): void;
}

export interface Command {
  id: string;
  title: string;
  group: CommandGroup;
  keywords?: string[];
  /** Shortcut spec string, see utils/shortcuts.ts ('mod+d', 'alt+arrowup'). */
  shortcut?: string;
  /** Extra shortcut specs that trigger the same command ('mod+y' for redo). */
  shortcuts?: string[];
  when?(ctx: CommandContext): boolean;
  run(ctx: CommandContext): void | Promise<void>;
  /** Not shown in the palette / menu (still runnable by shortcut and id). */
  hidden?: boolean;
  /** Fire the shortcut even while an input / contentEditable is focused. */
  allowWhileTyping?: boolean;
}

const registry = new Map<string, Command>();
const listeners = new Set<() => void>();
let snapshot: Command[] | null = null;

function changed() {
  snapshot = null;
  listeners.forEach((cb) => cb());
}

export function registerCommand(cmd: Command): () => void {
  registry.set(cmd.id, cmd);
  changed();
  return () => {
    // Only remove our own registration; a later re-register of the same id wins.
    if (registry.get(cmd.id) === cmd) {
      registry.delete(cmd.id);
      changed();
    }
  };
}

export function registerCommands(cmds: Command[]): () => void {
  const offs = cmds.map(registerCommand);
  return () => offs.forEach((off) => off());
}

/** Stable registration order; the same array instance until the registry changes. */
export function getCommands(): Command[] {
  if (!snapshot) snapshot = Array.from(registry.values());
  return snapshot;
}

export function getCommand(id: string): Command | undefined {
  return registry.get(id);
}

export function subscribeCommands(cb: () => void): () => void {
  listeners.add(cb);
  return () => {
    listeners.delete(cb);
  };
}

export function __resetCommandsForTests(): void {
  registry.clear();
  listeners.clear();
  snapshot = null;
}

export function useCommandContext(): CommandContext {
  // Collect a string key (not an array) so the hook only re-renders when the
  // selection actually changes.
  const { actions, query, selKey } = useEditor((state) => ({
    selKey: Array.from(state.events?.selected || []).join('\n'),
  }));
  const { device, setDevice } = useDevice();
  const pages = usePages();
  const { notify } = useNotices();
  const { open: openSitesmith } = useSitesmithModal();
  const { setTemplateModalOpen, setHeadCodeModalOpen } = useMobileChrome();

  return useMemo<CommandContext>(
    () => ({
      query,
      actions,
      selectedIds: selKey ? selKey.split('\n') : [],
      device,
      setDevice,
      pages,
      notify,
      openSitesmith,
      openTemplates: () => setTemplateModalOpen(true),
      openHeadCode: () => setHeadCodeModalOpen(true),
    }),
    [query, actions, selKey, device, setDevice, pages, notify, openSitesmith, setTemplateModalOpen, setHeadCodeModalOpen],
  );
}

/** Live selection read; collectors are snapshots and can lag a keydown. */
function liveContext(ctx: CommandContext): CommandContext {
  try {
    return { ...ctx, selectedIds: ctx.query.getEvent('selected').all() };
  } catch {
    return ctx;
  }
}

function isEnabled(cmd: Command, ctx: CommandContext): boolean {
  try {
    return cmd.when ? !!cmd.when(ctx) : true;
  } catch {
    return false;
  }
}

export function useRunCommand(): (id: string) => Promise<boolean> {
  const ctx = useCommandContext();
  const ref = useRef(ctx);
  ref.current = ctx;
  return useCallback(async (id: string) => {
    const cmd = getCommand(id);
    if (!cmd) return false;
    const c = liveContext(ref.current);
    if (!isEnabled(cmd, c)) return false;
    try {
      await cmd.run(c);
      return true;
    } catch (err) {
      console.error(`Command ${id} failed:`, err);
      return false;
    }
  }, []);
}

/** Keys that are also how focus / dialogs are driven: Tab walks focus and Esc
 *  dismisses. They only belong to the canvas when focus is on it (or the body),
 *  never while a button, link or dialog holds focus. */
function focusOutsideCanvas(el: Element | null): boolean {
  // An open modal owns Esc / Tab even when focus has not moved into it.
  if (document.querySelector('[role="dialog"][aria-modal="true"]')) return true;
  if (!el || el === document.body) return false;
  if (el.closest('[role="dialog"], [aria-modal="true"], .modal-backdrop')) return true;
  return !!el.closest('button, a[href], summary, [role="button"], [role="menuitem"], [role="tab"]');
}

function shortcutsOf(cmd: Command): string[] {
  return cmd.shortcut ? [cmd.shortcut, ...(cmd.shortcuts ?? [])] : [];
}

/**
 * Document-level keydown dispatcher: first registered command whose shortcut
 * matches and whose `when()` passes runs, with preventDefault. Mounted once, by
 * useKeyboardShortcuts (#39), so two listeners never double-fire.
 */
export function useCommandShortcuts(): void {
  const ctx = useCommandContext();
  const ref = useRef(ctx);
  ref.current = ctx;

  useEffect(() => {
    const onKeyDown = (e: KeyboardEvent) => {
      const typing = isTypingTarget(document.activeElement);
      const c = liveContext(ref.current);
      for (const cmd of getCommands()) {
        const hit = shortcutsOf(cmd).find((spec) => matchShortcut(e, spec));
        if (!hit) continue;
        if ((hit === 'tab' || hit === 'shift+tab' || hit === 'escape') && focusOutsideCanvas(document.activeElement)) continue;
        if (typing && !cmd.allowWhileTyping) continue;
        if (!isEnabled(cmd, c)) continue;
        e.preventDefault();
        try {
          Promise.resolve(cmd.run(c)).catch((err) => console.error(`Command ${cmd.id} failed:`, err));
        } catch (err) {
          console.error(`Command ${cmd.id} failed:`, err);
        }
        return;
      }
    };
    document.addEventListener('keydown', onKeyDown);
    return () => document.removeEventListener('keydown', onKeyDown);
  }, []);
}

/** Register commands for the lifetime of a component; re-registers when `deps` change. */
export function useRegisterCommands(cmds: Command[], deps: unknown[]): void {
  useEffect(() => registerCommands(cmds), deps); // eslint-disable-line react-hooks/exhaustive-deps
}